CO2, Blood pH and Respiratory Alkalosis: Causes and Effects

Blood pH is tightly regulated by a system of buffers that
continuously maintain it in a normal range of 7.35 to 7.45 (slightly
alkaline). Blood pH drop below 7 can lead to a coma and even death due
to severe acidosis. This causes depression of the central nervous
system. High blood pH (above 7.45) is called alkalosis. Severe
alkalosis (when blood pH is more than 8) can also lead to death, as it
often happens during last days or hours of life in most people who are chronically and
terminally ill.

Hyperventilation is the most common cause of
respiratory alkalosis.
Note that overbreathing is exceptionally common in people with chronic diseases
(for clinical studies, see the Homepage of this site).

The main mechanisms for blood pH maintenance and control

Carbon dioxide plays one of the central roles in respiratory alkalosis. Note, however, that tissue hypoxia due to critically-low
carbon dioxide level in the alveoli is usually the main
life-threatening factor in the severely sick. As we discussed before,
CO2 is crucial for vasodilation and
the Bohr effect.

Respiratory alkalosis caused by low CO2 in the arterial blood

This YouTube video clip "Hypocapnia,
Respiratory Alkalosis: Key Causes of Deaths In the Most Sick" summarizes
numerous epidemiological studies related to ineffective breathing in the
severely sick and critically ill people. Their breathing is very fast and deep, while oxygenation
of cells is critical. This is the reason why, regardless of the health
condition, critically ill patients are often provided with pure oxygen.
You can read all these medical abstracts on the web page
How do we breathe when we die?

Many people believe that if you eat certain foods, it can
cause your blood to become more alkaline or acidic. Medical research
studies have clearly shown that breathing and blood carbon dioxide and
bicarbonate ions levels are more significant factors in blood-pH
control. Alveolar hyperventilation that is common in
the sick reduces cell oxygenation, increases resting
blood lactate levels, intensifies production of free radicals due to
tissue hypoxia (cells are deprived of oxygen), causes diabetic
ketoacidosis in the genetically predisposed patients, and suppresses
the immune system and main blood-pH buffer systems of the human
organism.

Changes in
carbon dioxide and breathing cause immediate and long-term
effects of blood pH. They are not necessary the same. The immediate
effects are simple: higher-CO2 content causes blood acidification and
pH decrease, while reduced carbon dioxide levels increase blood pH, often causing
death in the critically ill (see a review of medical studies below).
Long-term effects depend on the direction of change (moving closer to
normal breathing or not), genetic factors, existing pathologies, diet,
physical exercise, thermoregulation, and many other parameters.

CO2 gas, when dissolved in blood, is the second largest group
of negative ions of blood plasma. Hence, breathing directly affects
blood pH. In its turn, blood pH is tightly monitored within a very
narrow range (from about 7.3 to 7.5) by the group of nerve cells
located in the medulla oblongata in order to have normal-body
biochemistry. The same nerve cells control breathing by through several
independent mechanisms, including peripheral and central CO2 and O2
chemoreceptors.

CO2, hypocapnia and viscosity of blood

CO2 also influences viscosity of blood. Acute hyperventilation and
arterial hypocapnia makes blood more viscous. This effect is a part of the
fight-and-flight response (an immediate reaction to stress). While useful in
a short run to prevent blood losses due to bleeding, increased blood
viscosity produces a large strain on the heart muscle and causes other
negative effects leading to, for example, thrombosis (formation
of a blood clot).

Dr. KP Buteyko and over 180 of his medical colleagues also found that CO2
controls and regulates composition and properties of many all other
bodily fluids, including secretions of the stomach, composition and
properties of saliva and mucus, pH of the urine. For example, for most
people, in conditions of hyperventilation, stomach and urinary pH
become too low (too acidic), promoting development of gastritis and
ulcers, or urinary stones. Apart from respiratory alkalosis,
there are many other negative effects of overbreathing.